Association of socioeconomic status and exercise capacity in adults with coronary heart disease (from the Heart and Soul Study).

Lower socioeconomic status (SES) was associated with reduced treadmill exercise capacity and predicted adverse cardiovascular outcomes. Why patients with low SES had reduced exercise capacity and whether this relation existed in patients with coronary heart disease (CHD) was not known. Using data from the Heart and Soul Study, the association of 4 indicators of SES (household income, education, housing status, and occupation) with treadmill exercise capacity was analyzed in 943 men and women with stable CHD. In multivariable linear regression models adjusted for demographic variables, co-morbidities, medication use, and health behaviors (smoking, alcohol use, body mass index, physical activity, and medication adherence), exercise capacity significantly decreased in a graded fashion from the highest to lowest categories of each SES variable (p <0.001 for all trends). Differences in exercise capacity between the lowest and highest SES categories were 2.4 METs for household income, 1.8 METs for education, 2.3 METs for housing, and 1.3 METs for occupation. In similarly adjusted logistic regression models comparing the lowest with the highest categories of SES, low SES was strongly associated with impaired exercise capacity (defined as <5 METs; odds ratios for income 5.5, 95% confidence interval [CI] 1.9 to 16.0; education 4.3, 95% CI 2.0 to 9.5; housing 4.5, 95% CI 2.1 to 9.6; and occupation 2.8, 95% CI 1.4 to 5.7, p <or=0.001 for all trends). In conclusion, 4 indicators of low SES were strongly associated with decreased exercise capacity in patients with CHD. Differences in traditional cardiac risk factors and health behaviors did not explain this association.